A technique suitable for decorating many types of textiles is the use of disperse dye inks. Disperse dyes are solid at room temperature but vaporize (sublimate) at elevated temperature and then condense back to solid when cooled. In the vapor state these dyes are adsorbed into polyester or nylon fibers and form a permanent image when cooled. These images are wash and abrasion resistant and do not alter the feel of the textile.
Sublimation printing is also suitable for decorating almost any hard good item that has a dye-receptive polymer coating such as polyester. More recently sublimation inks have found use in inkjet printers, particularly for decorating textiles.
The concept of heat transfer printing of sublimable dyes was demonstrated by Blake in 1968 when he produced an offset ink using a solvent dye and was able to transfer those dyes to a cloth substrate. Later the concept was extended to heat transfer inks for other conventional printing techniques. More recently both dry and liquid toners as well as inkjet inks have been designed to be printed by digital techniques onto coated or uncoated substrates and the dye subsequently transferred to a dye-receptive surface. These processes have become a convenient technique for decorating certain types of textiles and novelty items. While these digital techniques are suitable for their purpose there is still a need for a simple technique where crafters can customize items such as textiles, ceramics, and other novelty items. A solution to this problem is to use marking pens that contain a suitable ink. Such markers have become very common and are available with a variety of traditional and specialty inks. Fibrous nib-based markers are a particularly suitable solution for producing customized novelty items and it would be desirable to have a nib-based marker that contained sublimable dye-based inks.
A variety of fibrous nib constructions have been designed for use in marking pens where the nib functions to wick an ink from a reservoir and dispense the ink onto a substrate or other surface. There are at least three types of nib constructions. The earliest type nib was based on wool felt and these formed the basis of the so-called “felt-tip” markers. A second type nib construction is based on nonwoven synthetic fibers such as drawn nylon, polyethylene or polypropylene that are then combined with a resin such as melamine and the composition sintered or cured, and then milled to the desired shape. A third type fibrous nib is formed by compressing polymer particles to produce porous wicking fibers that can be formed into bundles of a desired shape. These synthetic nibs may also have grooves for improved ink flow. In each case the nib is designed to wick an ink along its length and deposit the ink at a tip. More detail on synthetic fiber porous nibs can be obtained in patents U.S. Pat. No. 5,672,021 to Herman et al., U.S. Pat. No. 5,885,020 to Rossi, U.S. Pat. No. 6,117,260 to Rossi, U.S. Pat. No. 5,909,978 to Giordano, et al. or U.S. Pat. No. 8,852,122 to Mao, et al. The synthetic fiber nibs have an advantage over felt nibs in that both aqueous or solvent inks as well as inks with high pigment loading can be used. These porous plastic nib pens have been used to dispense many different liquid solutions or dispersions for application in writing instruments, children's coloring markers, dry erase markers, and artist's decoration inks. Inks used for these applications are typically designed to print directly on a substrate and produce a permanent mark. Such ink compositions would include a polymeric binder to fix the pigment to the substrate. For example, U.S. Pat. No. 5,043,013 to Kluger, et al. discloses washable polymer-based inks and their possible use in nib-type markers. There is no indication that Kluger used pigment-based disperse dyes in these marker pens and particularly sublimation dye inks of the composition of the present disclosure. U.S. Pat. No. 6,561,713 to Sukhan discloses fibrous nib markers for printing an aluminum metallic pigment dispersion. U.S. Pat. No. 6,881,000 to Perlman discloses nib markers with large channels that allow deposition of large size phosphorescent pigments. U.S. Pat. No. 7,208,036 to Fukuo, et al. discloses water-based pigment compositions for use in similar nib markers. However this application also relates to using relatively large size aluminum pigments that do not form a stable dispersion. Disperse dyes are not mentioned in any of these applications.
The use of nib tip marking pens with sublimation inks is also known in the art. For example U.S. Pat. No. 4,062,644 issued to Graphic Magicians discloses a transfer ink to be used with a felt tip marker pen. There is no mention in this patent that the disperse dyes are milled to a specific small particle size and then suspended using dispersants that will help prevent dye particles from aggregating. Other disadvantages of the Graphic Magician inks relate to the use of resins and solvents that are not consumer friendly. U.S. Pat. No. 4,082,467 to Kaplan also discloses a felt-tip marker pen and dye dispersion of vaporizable disperse dyes. In this example the dye is first dispersed with linseed oil and includes 40-50% of a soluble resin such as hydrogenated resin. This dispersion is then diluted with water, additional soluble resin, and 80-90% of a polyalcohol. This composition also suffers the disadvantages of using soluble resin and undesirable solvents. U.S. Pat. No. 4,211,528 also discloses use of sublimable disperse dyes in felt tip marker pens. In this example the inventor formulates a dye solution rather than a dispersion of the disperse dye particles. This was accomplished by use of chlorinated solvents which are environmentally unfriendly and would not be accepted in today's commercial market. In each of the above examples the composition also included a soluble resin.
Many additional disperse dye-based sublimation ink compositions are known in the industry, particularly for use with ink jet printers, and the intended application was sublimation printing of textiles or hard goods. For example U.S. Pat. No. 4,725,849 to Koike describes a disperse dye composition for inkjet printing directly onto cloth that has been treated with a hydrophilic resin. The particular ink compositions contained 20% or higher concentrations of solvent and this would be undesirable for commercial nib marker use. The inventors also provided no indication that such inks could be used in nib markers. U.S. Pat. No. 5,642,141 to Hale describes a process for inkjet printing heat activated inks onto an intermediate substrate and subsequently heat transferring that ink to a substrate similar to the Graphic Magicians earlier patent. The '141 patent claims a broad range of ink compositions suitable for the inkjet printing but interestingly does not reference the earlier '849 patent that includes the same compositions. There are numerous additional inkjet ink patents included in the reference material where the claims relate to disperse dye compositions with varying types of surfactants, dispersants or solvents. These inkjet ink compositions are usually designed to have viscosity higher than that which is suitable for the current invention. For example, U.S. Pat. No. 8,425,029 to Sawgrass specifically mentions on p. 2, column 45 that jet inks with heat activated solids should have a viscosity in the range of 7 to 30 cps.
In each case these inkjet ink compositions would not be suitable for use in consumer-based nib markers. It should be readily apparent that for broad consumer use, especially with children, the chemical composition criteria of the sublimation inks will necessarily be more stringent than for commercial or industrial inkjet sublimation inks. A first issue is the use of solvents and chemicals that are now considered either toxic or environmentally unfriendly. A second issue is the stability of the ink compositions. It is difficult to maintain long-term dispersion of pigment-based disperse dye sublimation inks. If the dye particles aggregate the inks will clog the nib causing failure. A third issue relates to maintaining an environmentally friendly solvent mixture that will not dry prematurely. A fourth issue is formulating an ink with low enough viscosity such that the ink is wicked at a desired rate but not so low that the ink will puddle when it first contacts the substrate. Jet inks with viscosity less than about 10 cps have a tendency to “pool” on nozzle face plates. A fifth issue is the inclusion of polymer components where the polymer can soften and adhere to a decorated item. A sixth issue particularly related to current inkjet inks is the inclusion of certain specialty chemicals necessary for proper long-term operation of ink jet pens but not required or desired if used in a consumer nib marker. A seventh issue is the percentage of water in the composition. It is desirable for the ink to be primarily aqueous based but this is not the case with most industrial use inkjet inks. Some or all of the forgoing issues are addressed by the compositions and processes as provided herein.